Service HotlineSeveral concepts about high-strength bolts 1. According to the specified performance level of bolts above 8.8, they are called high-strength bolts. The current national standard only lists M39. For large-size specifications, especially those with a length greater than 10 to 15 times High-strength bolts, domestic production is still short-term. The difference between high-strength bolts and ordinary bolts: High-strength bolts can withstand larger loads than ordinary bolts of the same specification. High-strength outer hexagon bolts High-strength outer hexagon bolts are made of Q235 (ie A3). The material of high-strength bolts is 35# steel or other high-quality materials, which are heat-treated after being made to improve the strength. The difference between the two is the difference in material strength. From raw materials: High-strength bolts are made of high-strength materials. The screws, nuts and washers of high-strength bolts are all made of high-strength steel, such as No. 45 steel, 40 boron steel, 20 manganese titanium boron steel, 35CrMoA, etc. Ordinary bolts are usually made of Q235 (equivalent to A3 in the past) steel. In terms of strength grades: high-strength bolts are increasingly used. Two strength grades are commonly used, 8.8s and 10.9s, of which 10.9 is the majority. The strength level of ordinary bolts is lower, generally 4.4, 4.8, 5.6 and 8.8. High-strength bolts High-strength bolts are viewed from the force characteristics: high-strength bolts apply pretension and transmit external forces by friction. Ordinary bolt connection relies on the shear resistance of the bolt and the bearing of the hole wall to transmit the shear force. When the nut is tightened, the pre-pressure is very small, and its influence can be ignored. In addition to its high material strength, high-strength bolts also exert a large amount of pressure on the bolts. The pre-pressure generates extrusion force between the connecting components, so that there is a large friction force perpendicular to the direction of the screw, and the pre-pressure, anti-slip coefficient and steel type directly affect the bearing capacity of high-strength bolts. According to the force characteristics, it is divided into pressure type and friction type. The calculation methods of the two are different. The minimum specification of high-strength bolts is M12, and M16~M30 are commonly used. The performance of super-large bolts is unstable and should be used with caution in design.
At present, the commonly used fastener loosening prevention methods generally include non-removable anti-loosening solutions and friction-increasing anti-loosening solutions. The non-removable anti-loosening scheme uses welding, bonding or punch point riveting to change the detachable threaded connection into a non-detachable threaded connection. In the non-removable anti-loosening scheme, the threaded fasteners cannot be reused and the operation is troublesome. It is often used in some important occasions that require high anti-loosening performance without disassembly. The anti-loosening scheme that increases the frictional force uses the method of increasing the frictional force of the bolt (screw) head and the end face of the nut to achieve the purpose of anti-loosening. The anti-loosening solution that increases friction is not limited by space and can be disassembled repeatedly, but the reliability is poor. After a certain period of work, the anti-loosening effect will be reduced due to vibration and other reasons.
The purpose of Guangdong Yueluo Hardware Industry Co., Ltd. is to provide a new type of open blind rivet suitable for riveting of aluminum Al, steel St, and stainless steel SST sheets with foam material in the middle. The new rivet improves the mandrel process, adopts aluminum mandrel, the head of the mandrel has a pit for easy deformation, and there is a conical stop groove above the breakpoint of the mandrel. The mandrel can be caught by the stopper to prevent the nail head from being exposed. At the same time, lock the core rod not to loosen.
screw suitable for a variety of tools is a single-structure threaded part, including a screw body and a screw head. The outer surface of the screw body is processed with an external thread 1, and the outer side of the screw head is formed by six screw heads. Prismatic, the top surface of each edge of the outer hexagonal prism is a boss, between each boss is an end face groove 4, and the middle of each boss is provided with an end face hole 3; the inner side of the screw head is formed by six screw heads. The side surface 5 forms an inner hexagonal prism hole, and the bottom of the inner hexagonal prism hole is processed with a cross groove 13 .
1. When the main body is large-scale equipment, accessories need to be installed, such as sight glass, mechanical seal seat, deceleration frame, etc. The stud bolts used at this time, one end is screwed into the main body, and the other end is equipped with nuts after the accessories are installed. , Since the accessories are often disassembled, when the main body and the accessories are directly connected by bolts, the main body threads will be worn or damaged over time, and it is very convenient to use studs to replace them. 2. When the thickness of the connecting body is very large and the bolt length is very long, stud bolts will be used. The purpose of anti-loosening of stud connection In actual work, the external load has vibration, change, high temperature creep of the material, etc., which will reduce the friction force, the positive pressure in the thread pair disappears at a certain moment, and the friction force is zero, thus making the threaded connection loose. , if repeated action, the threaded connection will loosen and fail. Therefore, it is necessary to prevent loosening, otherwise it will affect the normal work and cause accidents.
We have many years of experience in the production and sales of screws, nuts, flat washers, etc. The main products are: furniture hardware accessories nuts, pressure riveting parts BSO, stainless steel hand nuts, self-tapping self-locking bolts and other products, we can provide you with suitable products for you. Fastener Solutions.
