What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Yueluo's thin plate rivet method, the thickness of the metal thin plate is less than 0.8mm. The convex rib extrudes the metal sheet adjacent to the rivet hole. The protruding rib is annular, and the protruding rib surrounds the rivet. The rivet head is provided with a positioning structure, the rivet head is provided with a positioning structure for docking the positioning structure, and the positioning structure and the positioning structure are mutually butted through the rivet to align the convex rib with the rivet
In view of the above situation, the technical problem to be solved by Guangdong Yueluo Hardware Industry Co., Ltd. is to provide a self-expanding semi-solid installation rivet, the purpose is to solve the existing connection between plastic shells, lightweight plates, insulating materials, circuit boards, or any other In the case of thin, light-weight materials, the grip and bonding force of the rivet itself on the mounting surface is weaker than that of the rivets that are screwed and installed by manual operation. The rivet structure needs to be improved and strengthened when the material is installed.
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 technical solution adopted by Guangdong Yueluo Hardware Industry Co., Ltd. to solve its technical problems is a special pull rivet for railway freight cars, which has a pull rivet body and a collar. The rod body is composed of polished rod section, locking ring groove section and tail thread section from top to bottom. Protectors are provided at the tail thread section to prevent rust and bad teeth in the tail thread section during use. , collision deformation, etc. Specifically, the tail thread segment has an external thread or an internal thread, and the protective member is a nut or a bolt.
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