What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Guangdong Yueluo Hardware Industry Co., Ltd. has upgraded and combined the fastening nut and the hexagonal nut to ensure the original function of the nut. The nut can be easily and safely disassembled by preparing practical small parts. The inner diameter of the lock ring is 0.1mm larger than that of the hexagonal nut, which is convenient for installation.
Today's advanced manufacturing represented by large aircraft, large power generation equipment, automobiles, high-speed trains, large ships, and large complete sets of equipment has entered an important development direction. As a result, fasteners will enter an important stage of development. High-strength bolts are used for the connection of important machinery, and repeated disassembly or various installation torque methods require extremely high-strength bolts. Therefore, the quality of its surface condition and thread accuracy will directly affect the service life and safety of the host. In order to improve the friction coefficient and avoid corrosion, seizure or sticking during use, the technical requirements stipulate that the surface should be treated with nickel phosphorus plating. The thickness of the coating is guaranteed to be within the range of 0.02 to 0.03 mm, and the coating is uniform, dense, and free of pinholes.
When the countersunk head screws and hexagon socket head bolts are produced by the cold heading process, the original structure of the steel will directly affect the forming ability of the cold heading process. In the process of cold heading, the plastic deformation of the local area can reach 60%-80%, so the steel must have good plasticity. When the chemical composition of the steel is constant, the metallographic structure is the key factor to determine the plasticity. It is generally believed that the coarse flaky pearlite is not conducive to cold heading forming, while the fine spherical pearlite can significantly improve the plastic deformation ability of the steel. For medium carbon steel and medium carbon alloy steel with a large amount of high-strength bolts, spheroidizing (softening) annealing is performed before cold heading, so as to obtain uniform and fine spheroidized pearlite to better meet the actual production needs. For the softening annealing of medium carbon steel wire rods, the heating temperature should be kept above and below the critical point of the steel, and the heating temperature should not be too high, otherwise tertiary cementite will precipitate along the grain boundary, resulting in cold heading cracking. The wire rod of medium carbon alloy steel is annealed by isothermal spheroidization. After heating at AC1+ (20-30%), the furnace is cooled to slightly lower than Ar1, the temperature is about 700 degrees Celsius for an isothermal period, and then the furnace is cooled to about 500 degrees Celsius and air-cooled. The metallographic structure of the steel changes from coarse to fine, from flake to spherical, and the cracking rate of cold heading will be greatly reduced. The general area of softening annealing temperature for 35\45\ML35\SWRCH35K steel is 715-735 degrees Celsius; while the general heating temperature for spheroidizing annealing of SCM435\40Cr\SCR435 steel is 740-770 degrees Celsius, and the isothermal temperature is 680-700 degrees Celsius.
screw is a tool that uses the physical and mathematical principles of the circular rotation and friction of an object to fasten the mechanism of the object step by step. When using screws to fasten objects and parts, it is often necessary to use screws with spring washers and flat washers to lock and fix the relative position, so as to improve the stability of the fastening connection and make the screws less prone to loosening. However, in the prior art, the method of manually inserting the spring washer and the flat washer in sequence is generally used, which not only increases the workload of the staff, but also makes the installation efficiency relatively low. On the other hand, the traditional screw with a gasket only has the function of fixing, Without the function of sealing, it cannot be applied to special equipment such as oil tanks and airtight cabins. Therefore, it is necessary to design a screw that can reduce the workload and have its own sealing structure.
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