What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
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.
In order to overcome the technical problem that the screws and nuts cannot be disassembled and assembled at the same time in the prior art, Guangdong Yueluo Hardware Industry Co., Ltd. provides a simple structure and can be quickly disassembled and assembled at the same time in a small space. screw and nut removal tool.
Most of the blind hole installation rivets have the characteristics of light weight, reliable connection, high strength, and convenient and quick installation. For example, blind rivets have been widely used in various aerospace vehicles.
As a commonly used data communication device, connectors are widely used in computers and TVs. Because common connectors such as D-SUB and DVI are composed of a male seat and a female seat, the iron shell of the male seat and the female seat is The corresponding position is provided with holes, the holes of the male seat are connected with rivets, and the holes of the female seat are correspondingly provided with screws for fixing. After the male seat and the female seat are connected, tighten the screws so that the male seat and the female seat are tightly connected together. When assembling on a computer or a TV, the rivet has a fixed assembly direction, and the fixation of the rivet direction is very important for assembly. However, there is no anti-rotation device on the iron shell hole connected with the rivet on the existing connector, and the rivet cannot be positioned during the assembly process, and it is easy to rotate and dislocate. production efficiency.
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