Service HotlineWhen 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.
There is an anti-theft screw, which can prevent the use of any disassembly tool for disassembly, and effectively plays the role of anti-theft. Its structure is that the anti-theft screw is composed of two parts; the upper part is a hexagonal part, and the lower part is a threaded part; the hexagonal part and the threaded part are connected in rotation; The core shell is formed with the lock core; the lock core is rotatably connected with the lock core shell. The shell of the lock cylinder is fixedly connected with the hexagonal piece, and the starting structure is as follows: a pin hole is arranged on the hexagonal piece; The lower part of the hexagonal part is provided with a polygonal hole, which is connected with the polygonal hole on the threaded part; the lower part of the lock cylinder is a threaded rod; the threaded rod is located in the polygonal hole; The edge block moves up and down in the polygonal hole. When working, slowly twist the hexagonal piece from left to right and turn the key at the same time to achieve the alignment of the upper and lower polygonal holes.
Welding stud is also called welding screw, which belongs to a kind of fastener connected with high strength and rigidity. Welding stud is the abbreviation of cylindrical head welding stud for arc stud welding. Industrial plant construction, highways, railways, bridges, towers, automobiles, energy, transportation facilities, airports, stations, power stations, pipeline supports, lifting machinery and other types of steel structures and other projects.
At present, there is an anti-theft T-bolt in the prior art, which is composed of a screw rod and a bolt head connected with the screw rod; the screw rod is composed of a polished rod and a threaded rod; a concave hole is provided at the bottom end of the screw rod; cylindrical, and the diameter of the cylindrical bolt head is larger than the diameter of the screw. When the above-mentioned anti-theft T-bolts are in use, the user usually hammers the concave hole at the bottom end of the screw with a hammer or other tool to deform it, destroy the thread structure on the screw, and fix the nut with a deformed object, so as to achieve anti-theft. Features
The traditional single-sided riveting process mainly adopts two methods: rivet nut connection and blind rivet connection. The efficiency of the rivet nut is low. If the hollow nut is used, the rigidity is insufficient, resulting in low connection strength. In addition, the torsion resistance of the rivet nut is low. If the rivet nut is used to obtain better torsion resistance, it is made into a hexagonal shape. Embedding, because the shape of the sheet metal opening also needs to be made into a corresponding hexagon, it is inconvenient to process.
We have many years of experience in the production and sales of screws, nuts, flat washers, etc. The main products are: precision bolts, lifting ring screws and screws, inner 6 angle bolts, enlarged metal washer mesons and other products, we can provide you with suitable fastening products for you piece solution.
