Bolts made of high-strength steel, or which require a large preload, can be called high-strength bolts. High-strength bolts are often used for the connection of bridges, rails, high-pressure and high-pressure equipment. Brittle fracture. High-strength bolts applied to high-pressure equipment. In order to ensure the sealing of the container, a large prestress is required.
The coupling of the high-strength bolts needs to be tightened during assembly so that the tightened threaded assembly receives a force before it is subjected to the working load, which is the pre-tightening force. The magnitude of the preload force directly affects the reliability, tightness of the high-strength bolt connection, the fatigue strength of the thread, the anti-loosening performance of the coupling pair, and the possibility of a gap or a relative slip between the components after the load is subjected to the load.
As with how to ensure a secure connection of bolts and nuts, it is important to properly select the appropriate tightening torque when tightening the machine screws. Proper, secure connections are directly related to the quality of the assembled product. Therefore, when tightening the machine screws, we should calculate a reasonable tightening torque. These torques of the fastening machine screws are much smaller than the torque of the fastening bolts and nuts.
1. Calculation of tightening torque of machine screws The commonly used formula for calculating the tightening torque of threaded fasteners is: T=D×K×P
Where: T: moment (Newton? m/inch? pound 1Nm=nine in.1b) D: outer diameter of the thread (1mm=0.03937 in) K: coefficient of friction of the nut (light rod bolt K=0.20 galvanized bolt K=0.22 Waxed or lubricated bolt K=0.10) P: Clamping force (generally 75% of the yield point tensile strength value)
Numerous facts prove that it is beneficial to increase the high-strength bolt pre-tightening force to improve the reliability of the fastening and avoid the above factors, but the excessive pre-tightening force will cause the high-strength bolt to be overstressed during the assembly tightening process. (Overload) and elongation or breakage, so it must be designed with high pre-tightening force and within the safe working range, so that high-strength bolts do not overload during the tightening process and the working load.
What we need is the correct preload. Excessive preload is harmful, too small is not beneficial. In most cases, a uniform preload is required. A set of threaded high-strength bolts. If the pre-tightening force is large or small, the high-strength bolts will be subjected to different forces and cannot bear the working load evenly. This group of couplings may be in a shorter time. Internal failure.
Bengbu Bangze Fastener Manufacturing Co., Ltd. is a private enterprise specializing in R&D, production and sales. It mainly produces various types of high-strength bolts and high-strength nuts. We sincerely welcome friends from all walks of life to contact us for business negotiation and exchange experience! In the fierce market competition, with better product quality and more honest cooperation attitude, we will provide services for new and old customers, so that the company will continue to grow and develop to create a brilliant future!
Ningbo Zhengtuo Fastener Co., Ltd. specializes in high-strength bolts, high-strength nuts, etc. Welcome to call 15632068777
