Service HotlineFrom the perspective of use: The bolted connection of the main components of the building structure is generally connected by high-strength bolts. Ordinary bolts can be reused, but high-strength bolts cannot be reused. High-strength bolts are generally used for permanent connections. The high-strength bolts are prestressed bolts. The friction type uses a torque wrench to apply the specified prestress, and the pressure type screw off the torx head. Ordinary bolts have poor shear performance and can be used in secondary structural parts. Ordinary bolts just need to be tightened. Ordinary bolts are generally 4.4, 4.8, 5.6 and 8.8. High-strength bolts are generally 8.8 and 10.9, of which 10.9 is mostly. Level 8.8 is the same level as 8.8S. The mechanical properties and calculation methods of ordinary bolts and high-strength bolts are different. The stress of high-strength bolts is firstly by applying a pre-tension force P inside, and then generating frictional resistance on the contact surface between the connected parts to bear the external load, while ordinary bolts directly bear the external load.
In the prior art, the electric screwdrivers in the automatic locking screw machines all adopt the suction method to absorb the screws. Such a structure is relatively complicated, and the design of the air circuit needs to be considered, and the phenomenon of material jamming is prone to occur, and it cannot be carried out due to the reason of the air circuit. Deep hole locking screws cause great trouble to users.
Blind rivets are a type of flying rivets for single-sided riveting, but they must be riveted manually, electrically, and automatically using special tools. This type of rivet is especially suitable for riveting occasions where it is inconvenient to use ordinary rivets and must be riveted from both sides, so it is widely used in construction, automobiles, ships, aircraft, machinery, electrical appliances, furniture and other products.
A double-nut self-locking fastener includes bolts, nuts, nuts, and elastic gaskets that can produce plastic deformation under pressure; the nut and the bolt are connected by threads, and one end of the nut is provided with an external thread; There is an inner thread in one end, and the inner thread of the nut and the outer thread of the nut constitute a thread pair; the other end of the nut is provided with a through hole, and the bolt passes through the through hole of the nut; when the nut and the nut are installed and tightened, the elastic gasket is located in the nut. between the bolt and the nut; a notch for cutting off the thread is arranged on the circumference of the bolt thread; the direction of the notch is parallel to the axial direction of the bolt.
Usually, the forming of the bolt head adopts cold heading plastic processing. Compared with the cutting process, the metal fiber (metal wire) is continuous along the shape of the product, and there is no cut in the middle, thus improving the strength of the product, especially the mechanical properties. The cold heading forming process includes cutting and forming, single-station single-click, double-click cold heading and multi-station automatic cold heading. An automatic cold heading machine performs multi-station processes such as stamping, heading forging, extrusion and diameter reduction in several forming dies. The processing characteristics of the original blank used by the single-station or multi-station automatic cold heading machine are determined by the size of the bar with a length of 5-6 meters or the wire rod with a weight of 1900-2000KG, that is, the characteristics of the processing technology. The point is that cold heading does not use pre-cut single blanks, but uses the automatic cold heading machine itself to cut and upset (if necessary) blanks from bars and wire rods. Before extruding the cavity, the blank must be shaped. A blank that meets the technological requirements can be obtained by shaping. Before upsetting, reducing and positive extrusion, the blank does not need to be shaped. After the blank is cut, it is sent to the upsetting and shaping station. This station can improve the quality of the blank, reduce the forming force of the next station by 15-17%, and prolong the life of the die, and the bolts can be made with multiple diameter reductions. The precision that can be achieved by cold heading is also related to the selection of the forming method and the procedure used. In addition, it also depends on the structural characteristics of the equipment used, the process characteristics and its state, the precision of the tool and die, the life and the degree of wear. For high-alloy steel used in cold heading forming and extrusion, the roughness of the working surface of the cemented carbide mold should not be greater than Ra=0.2um. When the roughness of the working surface of this type of mold reaches Ra=0.025-0.050um, it has the highest life.
We have many years of experience in the production and sales of screws, nuts, flat washers, etc. The main products are: outer hexagon anti-loose locking self-locking thickened nuts, machine wire umbrella head screws, flat washer spring washer set nuts, British standard nuts and nuts and other products, we can provide you with a fastener solution that suits you.
