What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
In view of the deficiencies of the prior art, a simple structure is provided, which can ensure that the nut body and the washer are assembled together during the production of the wheel nut, and will not be separated from each other in any occasion, so as to ensure the reliability of the assembly, and the nut will no longer appear. The wheel nut assembly that needs to be reassembled after use or placement saves time and effectively improves the convenience of the wheel nut when it is used or placed
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.
According to the properties of nuts, there are mainly national standard (GB), German standard (DIN), international standard (ISO), Japanese standard (JIS), American standard (ASTM/ANSI) and other standards. Among them, the national standard, German standard, and Japanese standard are represented by M (such as M8, M16), and the American system and the British system are represented by fractions or # (such as 8#, 10#, 1/4, 3/8). Commonly used national standard GB41 Ⅰ type hexagonal nut - C grade GB6170 Ⅰ type hexagonal nut - A, B grade GB6171 I type hexagonal nut - fine thread - A, B grade GB6172 hexagonal thin nut - A, B grade - chamfering GB6173 Hexagonal Thin Nut - Fine Thread - A, B Grade GB6174 Hexagon Thin Nut - B Grade - No Chamfer GB6175 II Hexagonal Nut - A, B Grade GB6176 II Type Hexagonal Nut - Fine Thread - A, B Grade GB6177 Hexagon Method Blue face nut - grade A GB55 hexagonal thick nut GB56 hexagonal super thick nut GB1229 large hexagonal nut (high strength for steel structure)
Plastic tree rivets are also called inverted tooth plastic rivets, also known as Christmas tree plastic rivets. The toothed flakes have good elasticity and can be directly manually pressed and installed in the round holes of the interference assembly. The toothed flakes can be installed according to the actual thickness and size. It can be fixed by self-adjustment. The design of the inverted tooth type is that the rivet is firmly fixed to the installation surface after installation, and it is not easy to be pulled out. It is suitable for fixing between soft materials such as foam, wood, rubber, and automobile interiors. Plastic tree rivets have excellent insulation, fire resistance, non-magnetic, heat insulation, light weight, high temperature resistance, high strength, corrosion resistance, and are widely used in various industrial fields.
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